Energy dissipating mechanisms

ABSTRACT

Energy dissipating mechanisms 10 (FIGS. 1 and 2) and 110 (FIG. 3) include stops 12 and 112 of hard metal having long, cylindrical bores 14 and 114 at the entrance ends of frustoconical die portions 16 and 116 and serving to receive and guide enlarged heads 18 and 118 of plungerlike members 20 and 120 having softer, extrudable, frustoconical portions 22 and 122. The stop 112 is free to float laterally in a counterbore 142 in a separable muzzle 127 attached to a barrel 132.

United States Patent [151 3,678,808 Hsu et a1. July 25, 1972 [54] ENERGY DISSIPATING MECHANISMS 3,399,817 9/1968 Diehl ..227/10 [721 Yang smug Idaho; 33223123.? 351323 3222158: 5331353512 Raymwd Pmland, 2,141,098 12/1938 Wahlstrom ..227 9 x [73] Assignee: Omark Industries, Inc., Portland, Oreg. 3,283,933 1 H1966 Neighol'n 6! 227/11 3,297,224 l/1967 Osborne 227/10 [221 9 3,319,862 /1967 Neighorn ..227/ pp No: 3,341,101 Butler 81 X 3,348,751 10/1967 Hennlng 227/10 X Related US, Application Data 3,399,817 9/1968 Diehl ..227/10 3,465,942 9/1969 Diehl 227/10 [631 commuanon 79698), 1969,3112"!- 3,469,504 9/1969 Neighorn .92/

doned.

Primary Examiner-Martin P. Schwadron [52] U.S. C1 ..92/85, 227/10 Assistant Examiner Lesne Payne [51] Int. Cl ..F01b 11/02 Auomey guckhom, more, Klarquist & Sparkman [58] Field olSearch ..92/85; 227/8, 4,10,11;

60/26.1; 173/127, 139, 267 57 ABSTRACT 6 R f C-ted Energy dissipating mechanisms 10 (FIGS. 1 and 2) and [5 1 e erences l (FIG. 3) include stops 12 and l 12 of hard metal having long, UNITED STATES PATENTS cylindrical bores 14 and 114 at the entrance ends of frustoconical die portions 16 and 1 l6 and serving to receive 2,141,098 12/1938 wzfhlstrom "227/9 x and guide enlarged heads 18 and 118 of plungerlike members 3,283,983 H966 Nelghom at 20 and 120 having softer, extrudable, frustoconical portions 312971224 967 9 "327/10 22 and 122. The stop 112 is free to float laterally in a counter- 3,319,862 5/1967 Nelghom "227/10 bore 142 in a separable muzzle 127 attached to a barrel 132. 3,341,101 9/1967 Butler et a1. ..227/10 X 3,348,751 10/1967 Henning ..227/10 X 5 Claims, 3 Drawing Figures 6 .III

WRQAW:

INVENTOR 5 YUNG SHING HSU RAYMOND V POMEROY IIW MEHWI BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS DESCRIPTION This invention relates to energy dissipating mechanisms, and more particularly to captive piston powder actuated tools.

In energy dissipating mechanisms known hitherto, there has been provided hard stops having tapered portions adapted to extrude softer tapered portions of plunger members when the latter are driven into the stops, and sometimes the enlarged head portions of the plunger members become bent as the plunger members are driven into the stops which prevents reuse of the plunger members. It would be desirable to provide energy dissipating mechanisms which prevent bending of the plunger members when the plunger members are driven into the stops.

An object of the invention is to provide new and improved energy dissipating mechanisms.

Another object of the invention is to provide new and improved captive piston power actuated tools.

A further object of the invention is to provide stops for captive pistons having long, close-fitting entrance guide portions to prevent bending of the captive pistons when they are overdriven.

Another object of the invention is to provide a powder actu ated tool having a muzzle detachably secured to a barrel thereof and provided with a counterbore adapted to receive a hard stop loosely therein to permit limited lateral floating of the stop.

The invention provides energy dissipating mechanisms in which stops of hard metal are provided with tapered extruding portions and long, cylindrical entrance portions which provide lateral support to heads of plunger members when the latter are driven into the stops and soft tapered portions thereof are extruded by the tapered extruding portions of the stops. An energy dissipating mechanism forming one specific embodiment of the invention includes a barrel, a muzzle member attached to and detachable from the barrel and having a counterbore therein for loosely receiving a stop of hard metal and permitting lateral movement of the stop in the muzzle member to permit the entrance portion to shift, if necessary, into perfect alignment with a close-fitting head of a captive piston when the head enters the entrance portion of the stop and the captive piston is overdriven so that a soft, tapered intermediate portion of the piston is partially extruded through a tapered extruding portion of the stop.

In the drawings:

FIG. 1 is a fragmentary, partially sectional, side elevation view of an energy dissipating mechanism forming one embodiment of the invention;

FIG. 2 is a view similar to FIG. 1 but with parts of the mechanism in different positions; and

FIG. 3 is a fragmentary, sectional view of an energy dissipating mechanism forming an alternate embodiment of the inventron.

Referring now in detail to the drawings, there is shown in FIGS. 1 and 2 an energy dissipating mechanism forming one embodiment of the invention and in the form of a powder actuated tool. The mechanism 10 includes a stop 12 of hard metal having a long entrance side guide 14, which, in the embodiment shown, is a long cylindrical bore or counterbore extending rearwardly from the entrance end of a fructoconical die portion 16. The stop may be separate from the barrel as shown, or may be integral with the barrel. The bore 14 serves to slidably receive in close-fitting relationship an enlarged cylindrical head or piston portion 18 of a plunger-like member or captive piston 20, which has a frustoconical or tapered portion 22 joining the head portion 18 to a smaller cylindrical ram or plunger portion 26 of the member 20. The tapered portion 22', before any overdriving occurs, is generally complementary to the frustoconical die portion 16, the portion 22 preferably subtending an angle of about 10 less than that of the die portion 16. The stop also has an exit bore 28 concentric with the tapered die portion 16 and the entrance bore 14 and of somewhat larger diameter than that of the plunger portion 26 and preferably tapered slightly from larger at its rear end adjacent the tapered die portion to smaller at its forward end, the angle of taper of the exit bore preferably being between 1 and 2. The exit end of the bore 28 is at a somewhat larger clearance counterbore 30 in a barrel 32 leading to a bore 34 in muzzle portion 36 of the barrel, a muzzle member 38 being screwed into a tapped counterbore 40 in the muzzle portion of the barrel. The stop 12 is press fitted into a counterbore 24 in the barrel 32 and abuts the end of the counterbore 24.

The barrel 32 is carried by a barrel housing 50 detachably secured to a breech housing 52 having a handle 54 and containing a breech block 56 and a firing mechanism (not shown). A ported carrier sleeve 60 has a chamber 62 for receiving a cartridge 64 and slidably carries the captive piston 20, which has a resilient ring 66 frictionally engaging the sleeve 60 to hold the piston in any desired set position prior to firing of the cartridge 64. The piston is adapted to drive a fastener pin (not shown) inserted into the bore 34 when the cartridge is fired. The sleeve 60 is insertable into and removably from a bore 70 in the barrel. The captive piston has an ejector pin 72.

The tapered portion 22 and the head 18 of the captive piston 20 have a low hardness and high ductility as compared with a high hardness and little or no ductility of the stop 12 so that, when the captive piston is overdriven, the energy is dissipated by extruding, by the tapered die portion 16, the tapered portion 22 and adjacent portion of the head portion 18. The long cylindrical entrance portion 14 fits closely on the head portion 18 and laterally supports it during overdriving so as to prevent bending of the head portion relative to the plunger portion 26. Preferably, the hardness of the stop is from 52 to 56 on the Rockwell C scale, the hardness of the plunger portion 26 is from 57 to 61 on the Rockwell C scale and the hardness of the tapered portion 22 and the head 18 is from 40 to 50 on the Rockwell C scale.

EMBODIMENT OF FIG. 3

An energy dissipating mechanism forming an alternate embodiment of the invention is identical to the mechanism 10 except that the mechanism 110 includes a stop 112 which is free to float laterally in a loose-fitting counterbore 142 in a muzzle 127 detachably secured to a barrel 132. A ductile head or piston portion 118 is provided in a plunger-like member or captive piston 120, which has a ductile frustoconical or tapered portion 122 generally complementary in shape to a tapered extrusion portion 116 of the stop and joining the head portion 118 to a smaller, hard, cylindrical ram or plunger por tion 126. The stop has a long cylindrical entrance bore 114 fitting closely but slidably on the head portion 118 of the piston. The muzzle 127 has a bore 134 adapted to receive a fastener (not shown) to be driven and also receive in somewhat close-fitting engagement the plunger portion 126 of the captive piston 120. The stop 112 has a planar end face 131 slidably abutting planar face 133 forming the bottom of counterbore 142 in the muzzle 127. A head or flange portion 170 of the stop overhangs end 145 of the muzzle. Reduced, threaded portion 147 of the muzzle is screwed into tapped counterbore 149 in the barrel 132 to lock the muzzle to the barrel. The stop 112 is of hard metal like that of the stop 12 and has a rounded entrance end portion 151 of the entrance bore 114. The stop 112 has a smaller, generally cylindrical exit bore 128 at the exit end of the extrusion portion 116 and somewhat larger in diameter than that of the plunger portion 126 of the captive piston and preferably has a slight taper of about 1 to 2, being larger at its entrance end which is adjacent the exit end of the extrusion portion 116 and smaller at its other end which is adjacent a somewhat enlarged entrance end portion of a tapered clearance bore tapering to the bore 134.

The stop 118 abuts the face 133, and there is a loose fit, from 0.001 to 0.002 inch clearance, between end 145 of the muzzle and shoulder 162. There also is a loose fit, from 0.001

to 0.002 inch clearance, between end face 164 and bottom 166 of the counterbore 149 in the barrel. The radial clearance between the counterbore 142 and body portion 168 of the stop also is between 0.001 and 0.002 inch to permit slight lateral shifting of the stop relative to the bore 134 to compensate for any eccentricity of the head portion 118 relative to the shank portion 126. There also is a radial clearance between head portion 170 of the stop and the counterbore 149, this clearance being greater than that between the body portion 168 and the counterbore 142.

Whenever the piston 120 is overdriven, the portion 122 of the piston engages the extrusion portion 116 of the stop 112, the head portion 118 fitting closely and slidably in the counterbore 114 and the shank portion 126 fitting closely and slidably in the bore 134 in the muzzle. Since the stop 112 is free to move laterally, it is shifted laterally if there is any eccentricity between the shank portion 126 and the head portion 118. Hence, bending or cocking of the shank portion 126 relative to the head portion 1 18 is prevented.

in the above-described energy-dissipating mechanisms and 110 the stops 12 and 112 prevent any portion of the captive piston from leaving the tool in the event of free flight firing of the mechanism or in the event that one of the mechanisms is fired against a soft object of insufficient resistance to prevent the piston from leaving the barrel if the stop were not present. Also, even if such overdriving of the piston occurs, the forward portion of the head portion is merely extruded and is reusable. Also, the piston is reusable, the guide 14 and 114 keeping the head portion 18 or 118 in alignment with the shank or plunger portion. The floating stop 1 12 also compensates for any eccentricity of the piston 120.

The specific taper angle of the die portion 16 is such as to prevent the piston from breaking or necking down. Also, the taper of the exit bore 28 prevents seizing.

What is claimed is:

1. In an energy dissipating mechanism,

a stop having a passage including a generally cylindrical entrance portion of a predetermined diameter, a generally cylindrical exit portion aligned with and substantially smaller in. diameter than the entrance portion and a tapered intermediate portion joining the entrance and exit portions,

a plunger member having a generally cylindrical head portion adapted to fit closely in the entrance portion of the passage, a plunger portion slidable in the exit portion of the passage and a tapered transition portion generally complementary to the tapered intermediate portion and joining the head portion and the plunger portion,

the stop being of a predetermined hardness and the transition portion and at least the portion of the head portion adjacent the transition portion being substantially less hard than the stop,

and barrel means holding the stop and having a first portion adapted to guide the head portion of the plunger member to the stop and a muzzle portion positioned beyond the stop adapted to guide the plunger portion of the plunger member,

the barrel means mounting the stop for limited lateral movement of the stop relative to the barrel means to permit the stop to be shifted laterally by the head portion of the plunger member when the head portion enters the entrance portion of the stop and the plunger portion of the plunger member is in the muzzle portion of the barrel means.

2. The energy dissipating mechanism of claim 1 wherein the barrel means includes a barrel housing, a barrel member fitting into the barrel housing and having a bore and a counterbore therein and a muzzle member having a bore and a coun terbore therein and secured to the end of the barrel member with the counterbores aligned with and adjacent each other, the counterbore in the muzzle member being smaller in diameter than the counterbore in the barrel member,

the stop member being positioned in the counterbores and having a forward cylindrical portion loose in the counterbore in the muzzle member and a head portion loose in the counterbore in the barrel member, the diameter of the head portion of the stop being larger than the counterbore in the muzzle member and the forward cylindrical portion of the stop bearing against the bottom of the counterbore in the muzzle member.

3. In a powder actuated tool,

a captive piston including a cylindrical shank portion of a predetermined diameter and of a predetermined hardness, a head portion concentric to the shank portion and of a diameter substantially greater than that of the shank portion and of a hardness substantially less than that of the shank portion, and a tapered transition portion between the shank portion and the head portion and of a hardness substantially less than that of the shank portion,

barrel means having, proceeding from the muzzle end toward the breech end, a muzzle bore portion of a diameter the same as that of the shank portion, a clearance portion larger in diameter than the muzzle bore portion, and a counterbore portion larger in diameter than the muzzle bore portion,

and a stop member of a hardness substantially greater than that of the transition portion and the head portion of the captive piston,

' the stop member being positioned in the barrel means at the muzzle end of the counterbore and having an exit bore portion of a diameter larger than that of the plunger portion and smaller than that of the head portion of the captive piston,

the stop member also having a cylindrical entrance bore portion aligned with the exit bore portion and of a diameter substantially the same as that of the head portion of the captive piston and also having a tapered transition portion joining the entrance bore and the exit bore and being generally complementary in shape to the transition portion of the captive piston,

the stop member fitting loosely in the counterbore portion of the barrel means and shiftable laterally relative to the bore means so that, upon the occurrence of overdriving of the captive piston, the stop member is shifted laterally to compensate for any eccentricity between the plunger portion and the head portion of the captive piston.

4. The powder actuated tool of claim 3 wherein the barrel means includes a barrel member and a muzzle member detachably secured to the muzzle end of the barrel member,

the muzzle member having therein the muzzle bore portion,

the clearance portion and a counterbore of a predetermined diameter greater than that of the clearance portion and less than that of the counterbore portion of the barrel means,

the stop member having an enlarged head portion and a cylindrical body portion of an external diameter substantially less than that of the counterbore in the muzzle member.

5. The powder actuated tool of claim 4 wherein the muzzle member and the barrel member include interlocking threaded portions. 

1. In an energy dissipating mechanism, a stop having a passage including a generally cylindrical entrance portion of a predetermined diameter, a generally cylindrical exit portion aligned with and substantially smaller in diameter than the entrance portion and a tapered intermediate portion joining the entrance and exit portions, a plunger member having a generally cylindrical head portion adapted to fit closely in the entrance portion of the passage, a plunger portion slidable in the exit portion of the passage and a tapered transition portion generally complementary to the tapered intermediate portion and joining the head portion and the plunger portion, the stop being of a predetermined hardness and the transition portion and at least the portion of the head portion adjacent the transition portion being substantially less hard than the stop, and barrel means holding the stop and having a first portion adapted to guide the head portion of the plunger member to the stop and a muzzle portion positioned beyond the stop adapted to guide the plunger portion of the plunger member, the barrel means mounting the stop for limited lateral movement of the stop relative to the barrel means to permit the stop to be shifted laterally by the head portion of the plunger member when the head portion enters the entrance portion of the stop and the plunger portion of the plunger member is in the muzzle portion of the barrel means.
 2. The energy dissipating mechanism of claim 1 wherein the barrel means includes a barrel housing, a barrel member fitting into the barrel housing and having a bore and a counterbore therein and a muzzle member having a bore and a counterbore therein and secured to the end of the barrel member with the counterbores aligned with and adjacent each other, the counterbore in the muzzle member being smaller in diameter than the counterbore in the barrel member, the stop member being positioned in the counterbores and having a forward cylindrical portion loose in the counterbore in the muzzle member and a head portion loose in the counterbore in the barrel member, the diameter of the head portion of the stop being larger than the counterbore in the muzzle member and the forward cylindrical portion of the stop bearing against the bottom of the counterbore in the muzzle member.
 3. In a powder actuated tool, a captive piston including a cylindrical shank portion of a predetermined diameter and of a predetermined hardness, a head portion concentric to the shank portion and of a diameter substantially greater than that of the shank portion and of a hardness substantially less than that of the shank portion, and a tapered transition portion between the shank portion and the head portion and of a hardness substantially less than that of the shank portion, barrel means having, proceeding from the muzzle end toward the breech end, a muzzle bore portion of a diameter the same as that of the shank portion, a clearance portion larger in diameter than the muzzle bore portion, and a counterbore portion larger in diameter than the muzzle bore portion, and a stop member of a hardness substantially greater than that of the transition portion and the head portion of the captive piston, the stop member being positioned in the barrel means at the muzzle end of the counterbore and having an exit bore portion of a diameter larger than that of the plunger portion and smaller than that of the head portion of the captive piston, the stop member also having a cylindrical entrance bore portion aligned with the exit bore portion and of a diameter substantially the same as that of the head portion of the captive piston and also having a tapered transition portion joining the entrance bore and the exit bore and being generally complementary in shape to the transition portion of the captive piston, the stop member fitting loosely in the counterbore portion of the barrel means and shiftable laterally relative to the bore means so tHat, upon the occurrence of overdriving of the captive piston, the stop member is shifted laterally to compensate for any eccentricity between the plunger portion and the head portion of the captive piston.
 4. The powder actuated tool of claim 3 wherein the barrel means includes a barrel member and a muzzle member detachably secured to the muzzle end of the barrel member, the muzzle member having therein the muzzle bore portion, the clearance portion and a counterbore of a predetermined diameter greater than that of the clearance portion and less than that of the counterbore portion of the barrel means, the stop member having an enlarged head portion and a cylindrical body portion of an external diameter substantially less than that of the counterbore in the muzzle member.
 5. The powder actuated tool of claim 4 wherein the muzzle member and the barrel member include interlocking threaded portions. 